alt Hacker NewsGovernments can print money.
But yes, you're right, the core problem is that in the USA, people need to justify their existence through labor. If they can't labor, they can't justify their existence (barring the slim few outliers on benefits, who are constantly under attack for being lazy or whatever).
However, if we take a step back and just consider reality for itself, we're just talking about resource allocation. Under the current system, the allocation of resources is dependent upon how much cash any given person can command, which is ostensibly connected to the value of their labor, but in reality, is clumpy and is connected first and foremost to how much cash they or their family historically had, and secondarily how valuable their labor is to capitalism, rather than to humanity. Thus investment bankers make 9x what teachers and EMTs make.
There's no reason we need to play that game. We can simply allocate the resources along more efficient terms, such as, taking the robot-harvested food, having robots put it in self driving trains and trucks, and having it delivered to people who need food.
What would the money be used for, though? It does not serve as viable nourishment or shelter.
Money is, after all, just a record of debt to facilitate trade so that transactions do not have to be completed immediately. Consider your job. You work so you can eat, but you might not be hungry at work. So, instead, you offer your employer a loan. The employer issues an IOU (money) to denote the promise to give you food later. Then, you take the IOU to the grocery store later and hand it back in to receive the food promised.
But in a world where a few people own all the core resources (land, minerals, etc.) and have all of their needs met by AI, they won't have any need for trade. They'll summon the AI to deliver anything they need.
It seems the only thing it might be able to serve is a record of who gets what after civil war captures the spoils from those rich few. But said civil war will require significant effort from all, perhaps even against their will; which is quite unlike a UBI system.